The present invention relates to methods of making dielectric materials of the kind known as glass-reacted-ceramics, and more particularly to such methods wherein the glass-ceramic reaction during sintering results in a downward shift in the Curie temperature. It is known that the inclusion of a low melting temperature glass in a ceramic dielectric material makes possible the sintering and densification of the combination at relatively low firing temperatures. For example see the patent to G. Maher, U.S. Pat. No. 619,220 issued Nov. 9, 1971, and assigned to the same assignee as the present invention. Such low firing dielectric materials are especially advantageous for use in monolithic ceramic capacitors that may include relatively low cost silver-palladium electrodes.
A glass-reacted-ceramic is described in my U.S. Pat. No. 3,885,941, issued May 27, 1975 and assigned to the same assignee wherein cadmium from the glass is reacted with the ceramic to provide a high dielectric constant and a downward shift in the Curie temperature.
It is an object of this invention to provide an improved process for making a glass-reacted-ceramic material having more uniform and predictable electrical properties.
It is a further object of this invention to provide a process for making such dielectric materials wherein a higher dielectric constant and a further lowered Curie temperature may be achieved.
It is a further object of this invention to provide an improved process for making a glass-reacted-ceramic wherein the sintering temperature may be reduced.
It is yet a further object of this invention to provide an improved process for making a glass-reacted-ceramic wherein firing kiln contamination and escape of toxic gases is reduced.